This invention relates to an information reading system adapted to read an optically readable code recorded on a recording medium in order to reproduce the original information, the code including data patterns representing a piece of information and markers to be used for determining the position for reading each of the data patterns.
U.S. Pat. No. 5,835,629 describes an image processing apparatus adapted to extract the area of a specific object (marker) defined by a predetermined contour from an image containing markers.
More specifically, the disclosed image processing apparatus raster scans an input of binary image data, extracts runs (hereinafter,referred to as streaks) constituting part of each of the markers and located within a predetermined area and defines a circumscribed tetragon for the extracted set of streaks to extract the area of each of the marker. This apparatus provides an advantage that markers. can be easily detected with a simple processing operation because the area of a marker can be extracted simply by using data on the size of the marker or the run length.
While the proposed apparatus is advantageous in that it can detects the area of a marker by using only the run length, it has to process a large volume of data and hence is not adapted to deal with software because the input binary image data has to be scanned on a pixel by pixel basis to extract black runs. Additionally, it is highly sensitive and detects noises such as stains and/or scars that are found in the input binary image data but should not be detected so that it requires particular attention to avoid detection of wrong runs due to stains and occurrences of missing runs due to scars.
In an attempt to avoid the above identified problems, the cited U.S. Patent also proposes an apparatus adapted to perform an operation of combination/separation/substitution on the set of streaks that has been detected depending on the state of contiguity of a newly extracted streak and also an apparatus adapted to cancel the detection of a marker if the area of the extracted marker exceeds a predetermined size. Then, any erroneous detection of runs due to stains and any occurrence of missing runs due to scars can be corrected and the area of a marker can be accurately extracted.
However, an apparatus according to the cited U.S. Patent is not satisfactory for extracting the area of a marker at high speed while avoiding the influence of stains and scars. For example, it takes too much time for determining the validity of each streak because all the input binary image data has to be processed on a pixel by pixel basis. Additionally, wrong runs that resemble streaks of a marker-can appear in a peripheral area of the image due to shading and/or other phenomena to give rise to a risk of detecting wrong streaks.
In short, an apparatus according to cited U.S. Patent is not satisfactory in terms of high speed extraction of a marker and elimination of disappeared markers and wrong markers and hence there is a demand for an improved information reading system.
Therefore, it is the object of the present invention to provide an information reading system adapted to carry out a processing operation of extracting a marker at high speed. and prevent missing data that have to be read out from taking place due to disappearance of a marker or appearance of a wrong marker.
According to an aspect of the present invention, there is provided an information reading system adapted to optically read a code optically readably recorded on an information recording medium and including data patterns recorded according to a given piece of information and markers of a predetermined size arranged with predetermined positional relationships relative to the data patterns and provided for use in determining the position for reading each of the data patterns,
the markers being optically identifiably recorded in a mode different from the mode of recording the data pattern,
the information reading system comprising:
an imaging section for imaging the code from the information recording medium;
an image memory section for storing at least a partial region of the image picked up by the imaging section;
an attribute determining section for determining the attributes of a unit of a predetermined number of adjacently located pixels, the number of pixels being determined on the basis of the size of the markers, in order to discriminate the markers from the data patterns in the image stored in the image memory section;
a marker detecting section for detecting the markers on the basis of the attributes determined by the attribute determining section; and
a data reading section for determining the positions for reading the data patterns on the basis of the positions of the markers detected by the marker detecting section and reading the data.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.